The present invention is directed to a magnetic tape cassette and more particularly to a magnetic tape cassette which includes a pair of tape reels having upper and lower flanges with teeth, and brake members engageable therewith for stopping the reels to prevent unauthorized rotation thereof.
As is well known in the art, a conventional video tape cassette has an elongated opening in the front surface and the opening is covered by a guard panel which is pivotally mounted on the cassette side wall. With the guard panel pivoted to the open position, the magnetic tape may be pulled out of the cassette through the opening.
When the reels in the cassette are turned by the operator carelessly or when the reels are turned unintentionally due to vibrations when the cassette is not in use, the tape wound on the reels is liable to run unintentionally. Accordingly, the slack tape adjacent the opening could be the cause of damage to the tape when the guard panel is opened or closed.
Accordingly, a mechanism is provided in such a conventional video tape cassette to prevent the occurrence of the above described difficulties which might occur when the tape is unintentionally slackened or pulled out of the cassette. For example, the peripheral portion of one of the flanges of each tape reel is formed into a flat tooth-shaped or saw-tooth-shaped gear and ratchet pawls are provided within the cassette for engagement with the gears. When the cassette is not in use, the ratchet pawls are engaged with the gears to prevent the tape from becoming slack. When the tape cassette is loaded into a video tape recorder (hereinafter referred to as a VTR) a brake release lever is inserted into the cassette to disengage the ratchet pawls from the gears. However, such an arrangement within a cassette is still disadvantageous with respect to the following points. When the cassette is loaded into the VTR as described above the braking ratchet pawls are released. Therefore, the cassette is in the standby state for starting of the VTR and may be maintained in such a standby state for a long period of time during which the tape may become slack due to vibrations or the like. For example, the video tape recorder is frequently carried about subsequent to the insertion of the cassette into the recorder. This is especially true in the case of small tape cassettes which are loaded into portable video cameras.